It is important to define which of the plant growth factors determines the yield level. During recent years in Latvia, in most cases it was moisture. Grain yield level mostly depends on meteorological conditions during the tillering stage. Plants do not utilize all water from precipitation. Rain water efficacy depends on soil granulometric composition and content of humus. Humus content could be considered as regulated factor. Important is also distribution of precipitation during the vegetation period as well as run-off of rain water which depends on micro-relief, soil tillage type, and direction in accordance with the slope gradient. It is very important for cereal growing in what conditions tillering is done, because during that time productive stems as well as ear sprouts are formed. The aim of this research was to determine the effect of soil moisture on the growth and development of winter wheat Triticum aestivum L. Field trials were carried out during 2005-2007 in Kurpnieki field at the Research and Study farm „Vecauce” of the Latvia University of Agriculture. A total of 47 points (distributed as a grid of 50×50 m) were selected for sampling in the winter wheat field. In both experimental years, the increasing soil moisture in spring had a significant positive effect on the flag leaf area, which, in its turn, increased also the level of grain yield. Partial correlation analysis showed that exclusion of organic matter content and altitude above the sea level as factors, changes soil moisture at different layers of the soil insignificantly.

Grain after enzymatic treatment, which is a starch-containing raw material, is used for ethanol production. Bioethanol production in Latvia began in 2006. Extraction of biofuels is a clean process, because the byproduct is used in various sectors of the economy. The bioethanol in Latvia was derived primarily from winter wheat, winter rye, and winter triticale. The objective of the research is to determine the different nitrogen fertiliser rates required for winter cereal crop yields and bioethanol outcome. The trials were carried out from 2005 to 2008 in Agricultural Science Centre of Latgale (Latvia). The method (ethanol outcome) is based on fermentation of saccharified cereal samples by yeast Saccharomyces cerevisiae followed by the calculation of ethanol outcome and speed of fermentation. The highest starch content was in winter wheat and winter triticale grain, but the lowest - in winter rye grains. A close negative correlation (p is less than 0.05) was found for winter triticale and winter wheat between the ethanol outcome and thousand grain weight. Production of bioethanol from rye starch content is used with full utilisation of grain. The winter wheat has the largest ethanol outcome from one hectare.

Winter rape (Brassica napus L.) significance among field crops is unchangeable for last decade in Latvia. Rape plant development in autumn, plant wintering and plant yielding is partly influenced by plant density. The aim of our research, started in autumn 2007 in the Research and Study farm ''Vecauce'', was to investigate the influence of agro-ecological factors (sowing date, sowing rate and fungicide (as growth regulator in autumn) application) on two type (line and F1) winter rape varieties' plant density in autumn, in spring and at harvesting. Plant density in autumn, in spring and during harvesting was determined also by meteorological parameters as air temperature and precipitation. Oilseed rape field germination was observed from 84% sown on 1st of August in 2007 till 67% sown on 1st of August in 2008. A significant impact (p is less than 0.05) of the sowing rate was noted for plant winter hardiness (in points) for variety 'Californium' in both years: 2008 and 2009. Fungicide application effect on plant survival during winter was observed for treatments with greater plants density. A very little average plant number decrease per square m during summer growth period was noted for all treatments in both years - within 1 to 4% in some cases. The tendency was observed that final plant density at harvest if greater sowing rates had been used, was never high on average for 'Californium' from 75 plants per 1 square m (120 germinable seeds per square m) to 60 plants per 1 square m (100 germinable seeds per square m) in 2009. Correlations between plant density at harvest time and seed yield were found.

Maize (Zea mays L.) is one of the agricultural plants that is suitable substrate for biogas production. Fresh as well as ensiled maize can be used as biogas substrate. Practically, mainly maize silage is used because fresh maize is available only for short term during the vegetative period. The paper is aimed to determine the impact of ensiling on substrate composition of maize hybrids. A field trial was carried out in the Research and Study farm ''Vecauce'' of the Latvia University of Agriculture (LLU) in 2008 and 2009. Ten (in 2008) to eleven (2009) maize hybrids with different maturity rating according to FAO numbers (FAO 180 – 340) were harvested at three different times beginning on 5 September at fourteen-day intervals. Chopped maize samples of 1-3 kg were ensiled in plastic silos. Samples of fresh and ensiled (for at least 90 days) maize were analyzed detecting 14 parameters in the Scientific Laboratory of Agronomy Research of LLU using standard methods. Our results showed that ensilaging influence on organic dry matter and hemi-cellulose content was not substantial. High (p is less than 0.05) correlation between organic dry matter content of fresh and ensiled samples was noted. The crude protein, crude fibre, ash and cellulose concentration was greater in the ensiled samples if compared with fresh maize samples in 2008 and 2009. After ensilaging process neutral detergent fibre (NDF) concentration was higher compared with fresh samples in 2009 but lower in 2008.

Precocity of fruit plants enables early obtaining of yield and income. But precocity can be influenced by drought. In some cases precocity is related to insufficient growth and insufficient yield in the succeeding years. The precocity of sour cherries was investigated in the trial established at the Latvia State Institute of Fruit Growing. Soil moisture treatments - woodchip mulch and drip irrigation as well as cultivars ‘Bulatnikovskaya’, ‘Desertnaya Morozovoi’, ‘Latvijas Zemais’, ‘Orlica’, ‘Shokoladnica’, ‘Tamaris’, and ‘Zentenes’ were used as trial factors. The flowering and yielding was observed in 2008 and 2009. Flowering, fruit set, fruit mass, and yield were characterized in order to evaluate precocity of cherries in different soil moisture treatment variants. The use of drip irrigation did not influence the yield of sour cherries, but the use of woodchip mulch decreased the yield in the third growing year. The cultivar ‘Tamaris’ was the most precocious, and the cultivar ‘Bulatnikovskaya’ was the most productive.

Cultivars of northern highbush blueberries (Vaccinium corymbosum L.) are the most suitable for areas with long, cold winter, because they require the greatest number of winter chilling hours. The blueberries are excellent sources of phytochemicals that are believed to have a significant biological activity. The experiment was done at the Institute of Agrobiotechnology, Latvia University of Agriculture, Jelgava, in the year 2009. The aim of the experiment was to evaluate phenological development of 9 highbush blueberry cultivars, their yield, fruit weight and biochemical composition: total anthocyanins, total phenols, ascorbic acid, titratable acids, and soluble solids. The obtained data showed correlation between duration of flowering and fruit ripening; between harvest and end of vegetation period of the highbush blueberry. The phenological development was dependent not only on cultivars, but also on the effective air temperature (above + 5 deg C). The research results allow assessing the phenology development of blueberry cultivars and predicting the fruit ripening time in conditions of Latvia. The most productive cultivars were 'Patriot' and 'Northland' The biggest single berry weight presented the cultivars 'Chippewa' and 'Bluejay'. The cultivar 'Jersey' had the highest content of titrable acid, anthocyanins, and ascorbic acid. The highest phenol content was detected in highbush blueberry cultivars 'Spartan' and 'Bluecrop'.

The lily (Lilium L.), a vegetative propagated perennial crop, is one of the economically most important flower bulb plants. It is cultivated worldwide as a cut flower, garden plant and pot plant. Lilies, 'the aristocrats of the garden', are very popular for their elegant flowers and stately habit, and offer the gardener an enormous range of colours, forms, and fragrances. The aim of this research was to evaluate the parent plants with the hybrids according to their morphological characteristics: plant height, flower diameter and inflorescence: number of flowers. In a trial, fourteen cross combinations were analyzed in 2006 – 2007. The evaluation was conducted in a lily breeding and growing farm 'Puķulejas', located in Saulkrasti, region of Riga, Latvia. The results showed that, if there were no significant differences in plant height between the parent plants, the hybrids were shorter than their parents. Male parents with short stems produced hybrids with shorter stems. Parental selections of medium and large number of flowers produced hybrids with comparatively large numbers of flowers on a stem, but if parents of different number of flowers were selected, in hybrids the smaller count dominated or prevailed.

Genotypes of CSN3 gene were detected in 71 individuals of Latvian Blue breed and in 30 individuals of Latvian Brown breed using a PCR-RFLP method. Animals were chosen at random from each heard. This study investigated the alleles A and B of CSN3 gene, while determining the allele and genotype frequencies and Hardy-Weinberg equilibrium proportions in both populations. The results showed that in our analyzed samples from 71 Latvian Blue breed only 7 animals (10%) had the genotype BB, and in analyzed samples from 30 Latvian Brown breed only 3 had the genotype BB (10%). Frequencies of CSN3 genotypes AA, AB, and BB correspond to Hardy-Weinberg equilibrium proportions and populations in genetic equilibrium. A wide variation in the B allele frequency among Latvian Blue and Latvian Brown breeds was found suggesting that molecular selection for animals carrying the allele B of CSN3 could impact breeding programs for dairy production in Latvia.

One of the primary reasons for expanding the production and use of biofuels is the potential environmental benefit that can be obtained from replacing fossil fuels with fuels derived from renewable biomass resources. This investigation examines the impact of biofuels on the environment directly from the practical view point analysing how the internal combustion engine emission concentration changes using the most common first-generation biofuels in Latvia – biodiesel, rapeseed oil and bioethanol. Laboratory experiments were performed on a chassis dynamometer Mustang MD1750, but the content of exhaust gases components was determined by the AV L SESAM FTIR measurement system. Investigation shows that the trends of different exhaust gas component changes, which would be the same for all investigated fuels, don't exist, i.e., each vehicle and biofuel type or blend is particular and has to be analysed separately. In comparison with fossil diesel, running the car VW Golf on rapeseed oil the average reduction of NOx was 10%, but SO2 – 59%. The CO, CO2, unburned hydrocarbon and mechanical particle emissions were higher. Running the car Opel Vectra on biodiesel the amount of NOx in comparison with fossil diesel increased in average by about 12%, the amount of mechanical particles and unburned hydrocarbons decreased quite significantly, but just a small increase of CO and SO2 was observed. Testing the car VW Passat on gasoline-bioethanol blends increase of the bioethanol content in the fuel blend increased also the NOx content in exhaust gases, but the content of CO, CO2 and NH3 decreased.

The utilization of traditional fossil fuels (oil, gas) as primary energy resources causes a destabilization of the eco-environmental situation in the world. Latvia has to significantly decrease energy imports from its neighbouring countries. This can be achieved by using high-quality local primary renewable energy sources. One of the solutions is to utilize anaerobic fermentation for biogas production. This process can be ensured by utilizing manure, food waste as well as energy biomass - wood, grass and maize. Biogas is utilized as a primary energy source in a cogeneration plant which is a combined cycle plant for electricity and heat power production. Microcogeneration plant for farming household needs would ensure an independent power supply, in case the overall electrical network is in a state of emergency. In order to ensure optimal biogas yield, which, in turn, would ensure a stable operation of the microcogeneration plant, it is important to know the parameters and quality of the biomass that have been filled in bioreactor. This research deals with the influence of the linkage biomass type on the qualitative and quantitative indicators of biogas. As a result, it has been found that biomass type affected the methane percentage in biogas greatly. The methane content of biogas independent with biomass type was diminished from 65% (galega) to 44.5% (fresh sawdust), but biogas yield decreased from 0.627 m**3 kgVSd E-1 (galega) to 0.185 m**3 kgVSd E-1 (fresh sawdust).